Robust Conceptual Design of Transonic Airfoils

This paper describes an integrated, multi-fidelity analysis and heuristic design approach that can be used to derive initial airfoil designs for transonic flight. If successful, the final result is a geometry that can be expected to produce reasonable aerodynamic performance when used with higher order analysis methods. A key aspect of the methodology is the use of a sonic-plateau pressure distribution as the target distribution for inverse design. The sonic- plateau distribution is easily parameterized and has the advantage of automatically resulting in a smooth airfoil shape without any discontinuities built into the surface due to the presence of a shock in the target pressure distribution. Inverse design is performed on each airfoil using a parametrically defined pressure distribution at a reduced lift coefficient and Mach number from the design condition. The methodology is demonstrated by designing an airfoil at 38% of the wing semispan for a 737-200-like aircraft. The demonstration problem shows that the methodology is able to achieve rapid and robust convergence to the solution. The calculated designed airfoil was found to be sufficiently higher than Mach number, and the maximum thickness was close to the targeted value

Issues concerning the Admissibility in Federal Courts of Business Records Containing Opinions or Diagnoses under Federal Rule of Evidence 803(6)

Federal Rule of Evidence 803(6) explicitly provides for the admissibility in the federal courts of business records containing opinions or diagnoses. Despite that, over the years, the courts have routinely excluded business records containing opinions and diagnoses for a variety of reasons. In 1979, for example, the Court of Claims fashioned a rule preventing the admission of expert appraisals unless the preparer of the appraisal were present to testify to his qualifications as an expert pursuant to Rules 702 and 705. Many courts continue to follow this rule. This note discusses and critiques that rationale for exclusion (and others), in light of more current jurisprudence concerning opinions, experts, and expert opinions

Survey of marine cercariae from the coasts of Marin and Sonoma Counties, California

This study deals with the cercarial fauna of marine mollusks in the littoral zone and estuaries of the California coast between Duxbury Reef and Fort Ross. The investigation began in June, 1968 at the Pacific Marine Station, Dillon Beach, California and continued through July, 1969, with monthly collections at various localities (see map). Two major objectives were aimed at: first, to continue a survey of the cercariae of the area begun by Fisk (194) and second, to establish a basis for future life history studies

Semi-Empirical Prediction of Aircraft Low-Speed Aerodynamic Characteristics

This paper lays out a comprehensive methodology for computing a low-speed, high-lift polar, without requiring additional details about the aircraft design beyond what is typically available at the conceptual design stage. Introducing low-order, physics-based aerodynamic analyses allows the methodology to be more applicable to unconventional aircraft concepts than traditional, fully-empirical methods. The methodology uses empirical relationships for flap lift effectiveness, chord extension, drag-coefficient increment and maximum lift coefficient of various types of flap systems as a function of flap deflection, and combines these increments with the characteristics of the unflapped airfoils. Once the aerodynamic characteristics of the flapped sections are known, a vortex-lattice analysis calculates the three-dimensional lift, drag and moment coefficients of the whole aircraft configuration. This paper details the results of two validation cases: a supercritical airfoil model with several types of flaps; and a 12-foot, full-span aircraft model with slats and double-slotted flaps

Acroneuria lycorias (Boreal Stonefly, Plecoptera: Perlidae) Emergence Behaviors Discovered in Pinus strobus Canopy

Species of Plecoptera, or stoneflies, are known to use vertical emergence supports, and researchers believe many species of Plecoptera exploit arboreal habitats during emergence. However, the exact nature of these arboreal behaviors has largely remained a mystery. While exploring the habitat potential of Pinus strobus (L.) (Eastern White Pine) canopies in northern Wisconsin we observed Acroneuria lycorias (Newman) (Boreal Stonefly, Plecoptera: Perlidae) exuviae at heights as high as 12m (observations at 6.6, 9, 9.5, and 12m). Most A. lycorias exuviae appeared to have a strong preference for emergence sites at the underside or base of branches similar to some Odonate species. We also observed A. lycorias, adults climbing upwards along the main stem, post-emergence, to heights up to 22m. To our knowledge, these heights represent the greatest heights ever documented for A. lycorias adults and exuviae, or any Plecopteran species. While other researchers have speculated that A. lycorias uses arboreal habitats during emergence, these behaviors were considered almost impossible to describe. Our observations provide us with new insights into Plecopteran emergence behaviors, especially for this species. We propose three alternative hypotheses that may explain these unique emergence behaviors

Fixation of Rotor Laminate in an Electric Machine

In the future it is expected to exist twice as many cars on the roads as it does today. For companies manufacturing electric cars, such as Volvo Cars, hundreds of millions of traction motors must be produced. Therefore, an efficient and safe way of doing this is of great interest. Today, Volvo Cars assembles the rotor onto the shaft using a shrink-fit method where the rotor stack is heated and the shaft is cooled using liquid nitrogen. A new solution that can achieve the requests on the motor without using liquid nitrogen as cooling would simplify the assembly process, make it safer, and reduce the manufacturing costs. Alternative geometries to the regular circular shaft and rotor were investigated in this work by creating models using ANSA and analysing them with Abaqus. The geometry of the interference between shaft and rotor that was produced from this investigation is called valleys. It is based from the already existing shaft, but with circular cutouts around the outer edge. The cutouts are supposed to match a grinding tool to obtain a high manufacturability. The chosen solution was optimized against torque capacity, slip angle and fatigue life. The design is not final since the model has not yet been tested with any temperature gradient across the assemble, which may affect the contact between rotor and shaft. Real life testing is also necessary to ensure that the simulations are resembling the reality

Three-Dimensional Piecewise-Continuous Class-Shape Transformation of Wings

Class-Shape Transformation (CST) is a popular method for creating analytical representations of the surface coordinates of various components of aerospace vehicles. A wide variety of two- and three-dimensional shapes can be represented analytically using only a modest number of parameters, and the surface representation is smooth and continuous to as fine a degree as desired. This paper expands upon the original two-dimensional representation of airfoils to develop a generalized three-dimensional CST parametrization scheme that is suitable for a wider range of aircraft wings than previous formulations, including wings with significant non-planar shapes such as blended winglets and box wings. The method uses individual functions for the spanwise variation of airfoil shape, chord, thickness, twist, and reference axis coordinates to build up the complete wing shape. An alternative formulation parameterizes the slopes of the reference axis coordinates in order to relate the spanwise variation to the tangents of the sweep and dihedral angles. Also discussed are methods for fitting existing wing surface coordinates, including the use of piecewise equations to handle discontinuities, and mathematical formulations of geometric continuity constraints. A subsonic transport wing model is used as an example problem to illustrate the application of the methodology and to quantify the effects of piecewise representation and curvature constraints

Three-Dimensional Modeling of Aircraft High-Lift Components with Vehicle Sketch Pad

Vehicle Sketch Pad (OpenVSP) is a parametric geometry modeler that has been used extensively for conceptual design studies of aircraft, including studies using higher-order analysis. OpenVSP can model flap and slat surfaces using simple shearing of the airfoil coordinates, which is an appropriate level of complexity for lower-order aerodynamic analysis methods. For three-dimensional analysis, however, there is not a built-in method for defining the high-lift components in OpenVSP in a realistic manner, or for controlling their complex motions in a parametric manner that is intuitive to the designer. This paper seeks instead to utilize OpenVSP's existing capabilities, and establish a set of best practices for modeling high-lift components at a level of complexity suitable for higher-order analysis methods. Techniques are described for modeling the flap and slat components as separate three-dimensional surfaces, and for controlling their motion using simple parameters defined in the local hinge-axis frame of reference. To demonstrate the methodology, an OpenVSP model for the Energy-Efficient Transport (EET) AR12 wind-tunnel model has been created, taking advantage of OpenVSP's Advanced Parameter Linking capability to translate the motions of the high-lift components from the hinge-axis coordinate system to a set of transformations in OpenVSP's frame of reference